I HAVE TWO COMPLETE CARS. THE 2.3 IS A 93 LX CONVERTIBLE AND THE 5.0 IS A 90 GT HATCH. WILL THE WIRING HARNESS FOR THE UNDER DASH PLUG IN AND WORK. WHAT ELSE DO I NEED OFF OF THE GT. THANKS
The "car harness" wont work from the 90 IIRC. The 91-93 cars are different with the airbags and all of that. I didn't swap the harness itself, but instead pulled the pins out of the green plug under the dash by the brake booster and re pined it to work with one plug off the 5.0 harness. It works fine that way. Just know that your airbags wont work any longer (if the 90 doesn't have airbags.)
I hope thats right it was a while since I've done the swap. All I did though was get a complete wiring diagram for each cars (87Gt and 91Notch 2.3) and just drew up my own diagram and worked from there. You will also need to get the fuel pump relay as the 2.3L has it integrated into the ECU. It will be under the seat, I relocated mine to be under the dash with the computer as well as some other relays (again, can't remember) I'll look today and take pictures for you if you would like. Also I'm sure more knowledgable members will get on here and straighten it out.